KR20010053117A - Projection system - Google Patents

Abstract

The projection system includes at least two light sources, a projection lens and a spatial light modulator positioned between the light sources and the projection lens, the light modulator being a plurality of light-deflecting devices each provided with elements that can be tilted at an angle with respect to the tilt axis. Equipped with. The light sources are disposed with respect to the spatial light modulator in such a way that the centers of the light beams coming from the light sources and projected onto each element in operation are located on a projection line extending substantially parallel to the tilt axis of the element.

Description

Projection system

Spatial light modulators are understood to average analog or digital mirror devices (such as TMAs or DMDs) as well as eidophors whose reflection characteristics may be changed, and other light modulators may be changed in the direction of the light beam. .

In such a projection system, it is known from EP-A2-0 740 178 and the spatial light modulator is illuminated by means of two light sources. The spatial light modulator has a plurality of light-deflecting devices, each provided with elements that can be tilted at an angle with respect to the tilt axis. Each element can be tilted individually at an angle from the position that directs the light towards the projection lens to the position that directs the light away from the projection lens and vice versa. Condenser lenses that direct light from the light source to the first optical axis are associated with each light source. The projection system is further provided with a cylindrical lens located on the first optical axis, the lens receiving light from each condensing lens. The light then passes through the exit condensing lens and then directed to the spatial light modulator.

A disadvantage of the known projection system is that the tilt directions of the individual elements of the spatial light modulator do not take into account when the light sources are located, so there is a risk that an optimum output is not obtained.

The present invention relates to a projection system having at least two light sources, a projection lens and at least one spatial light modulator between the light sources and the projection lens, wherein the light modulators tilt in parallel to one another. There are a number of light-deflection devices each including elements that are tiltable about the tilt axis.

1 shows a projection system with one light source.

2 shows an element of a spatial light modulator.

3 illustrates the operation of a spatial light modulator.

4 is a plan view of a first embodiment of a projection system according to the invention;

5 is a side view of the projection system shown in FIG. 4.

6 shows an integrator plate of a second embodiment of a projection system according to the invention.

7 shows a third embodiment of a projection system according to the invention.

8A and 8B show the inlet and outlet sides of the integrator bar of the projection system shown in FIG.

FIG. 9 shows an integrator plate of the projection system shown in FIG. 7. FIG.

It is an object of the present invention to provide a projection system which can be provided with a plurality of light sources while obtaining an optimum light output.

The object is arranged for the spatial light modulator in such a way that the centers of the light beams coming from the light sources and projected onto each element in operation are located on a projection line extending substantially parallel to the tilt axis of the element. Obtained in the projection system according to the invention.

Since light spots coming from the light source are located on a connection line that extends parallel to the tilt axis, light coming from all light sources will enter the element and will deflect in the same direction when the element is tilted at an angle.

Corresponding elements in the figures are indicated by the same reference numerals.

1 shows an integrator bar 6 located in a light source 2, a lens 3 preceding the light source, a rotatable color filter 4 preceding the lens 3, and an optical light path 5 of the light source 2. ), A deflection mirror (7) located on the side of the integrator bar (6) away from the light source, a total internal reflection (TIR) prism (8) located in the optical optical path, a digital closest to the TIR prism A known projection system 1 is shown having a spatial light modulator with a digital mirror device (DMD) 9 and a projection lens 10 located on another side of the TIR prism. The optical path 5 also extends from the DMD 9 as an image optical path 11.

2 shows a digital light-deflecting device 12 provided with an element 14 which can be tilted at an angle with respect to the tilt axis 13. Component 14 may be tilted at an angle between two remaining states. Such digital light-reflective devices are known per se and in particular are evident from the aforementioned European patent application EP-A2-0 740 178 and will therefore not be described further. Currently commercially available digital light-deflecting devices 12 include rectangular elements 14, which are inclined at an angle with respect to the tilt axis 13 extending parallel to the diagonal of the rectangular element 14. Can be.

3 exemplarily shows the operation of a plurality of digital light-deflecting devices 12 ', 12 " and 12' " illuminated by a light source 2, the light being directed towards the projection lens 10. FIG. Can be directed. The light-deflecting devices 12 '' and 12 '' 'are tilted at an angle in the same way as the light beams 15' 'and 15' '' coming from the light source 2 are deflected toward the projection lens 10. . However, element 14 ′ of light-deflecting device 12 ′ is tilted at an angle in such a way that light beam 15 ′ coming from light source 2 is deflected away from projection lens 10. If the element 14 'is tilted obliquely in the same direction as the element of the light-deflecting devices 12 " and 12' " side by side, the light beam 15 ' 10).

4 and 5 show a plan view of a first embodiment of a projection system 17 according to the invention in which two light sources 2 ′, 2 ″ are provided, followed by lenses 3 ′, 3 ″, respectively; Side view. The optical axes 18, 19 of the light sources 2 ′, 2 ″ are perpendicular to each other as evident in FIG. 4. As will be apparent in FIG. 5, the optical axes 18, 19 intersect each other at a distance 20. The projection system 17 is provided with an integrator bar 21 having an inlet side 22 and an outlet side 23. In the vicinity of the inlet side 22 coming from the light sources 2 ', 2' ', the light beams 24, 25 are then connected to each other. For this purpose, the deflection mirror 26 is arranged in the optical light path 19 of the light source 2 '', by which the light beam 25 is deflected in a direction extending in parallel with the light beam 24. The integrator bar 21 has a height H and a width B1 in the vicinity of the inlet side and a height H and a width B2 in the vicinity of the outlet side 23. For example, the ratio H: B1 is 7: 4 while the ratio H: B2 is 3: 4. Due to the width B1 substantially twice the width B2 near the exit side, the light beams coming from the light sources 2 ', 2' 'are next connected to each other in the integrator bar 21.

The projection system 17 further includes a color filter 4, a deflection mirror 7, a TIR prism 8, a DMD 9 and a projection lens 10. In order to optimize the coupling-in of the two light beams at the integrator bar 21, the color filter 4 is not at or near the inlet side 22 as in the system of FIG. 1. It is arranged in the vicinity of the side 23.

Light beams coming from the light sources 2 ′, 2 ″ are projected through the optical path 5 to the elements 14 of the light-deflecting devices 12. The light sources 2 ', 2' 'are arranged in such a way that the centers of the light spots on each element 14 are located in a projection line coincident with the tilt axis 13 of the relevant element 14. That is, the light sources 2 ′, 2 ″ have the shortest connection line 27 between the optical axes 18, 19 of the light sources 2 ′, 2 ″ projected on each element 14. It is arranged in the same way as for the tilt axis 13 of the elements 14, extending parallel to the tilt axis of 14. Since the elements 14 perform only a small tilt of about 10 °, the optical output of the two light sources 2 ', 2' 'will be assured in this way.

6 shows an integrator plate 28 that can be used in the second embodiment of the projection system according to the invention. The projection system corresponds to the projection system shown in FIGS. 4 and 5, wherein the integrator bar 21 is projected on the DMD 9 by a second integrator plate disposed below the first integrator plate. Repositioned by integrator plate 28. The second integrator plate may be the same as the first integrator plate or may be optimized for light sources. The integrator plate 28 has a parallelepiped outer circumference and is provided with a number of rectangular integrator lens elements 20. The ratio between the height h and the width b of each lens element 29 corresponds to the height / width ratio of the DMD 9. The integrator plate 28 has a light beam 24 coming from the light source 2 'illuminating the upper left corner of the integrator plate 28, while the light beam 25 coming from the light source 2' 'has an integrator plate ( It is arranged in front of the light sources 2 ', 2' 'in the same way as illuminating the lower right corner of 28). In practice, the boundaries of each light beam 24, 25 are less sharply defined. The centers M of the light beams 24, 25 are located on the connection line L extending in parallel with the longitudinal side 30 of the parallelepiped 28. The longitudinal side 30 of the integrator plate 28 forms an angle α of about 45 ° with the side of the elements 29. The angle α corresponds to the angle β formed between the sides of the rectangular element 14 and the tilt axis 13.

7-9 show a third system 31 of the projection system according to the invention and differ from the projection system 18 shown in FIGS. 4 and 5. That is, the integrator bar 32 is provided in place of the integrator bar 21, and the integrator plates 33 and 34 are disposed closest to the outlet side of the integrator bar 32. The integrator bar 32 is rectangular near the inlet side 35 (shown in FIG. 8A), and the light beams 24, 25 from the light sources 2 ′, 2 ″ are next to each other at the inlet side ( 35) is projected. The integrator bar 32 forms an angle α of 45 ° with respect to the incoming light beam 24. The integrator bar 32 is also rectangular near the exit side 36. The integrator plate 33 corresponding to the integrator plate 28 is located near the exit side 36, and the integrator plate 33 receives the rectangular light beam 37 from the integrator bar 32. Due to the different integrator lens element 29, the light beam 37 is even more uniform. The light beam 37 forms an angle α of 45 ° with the sides of the integrator lens elements 29. As described above with reference to FIG. 6, the light beams 24, 25 coming from the light sources 2 ′, 2 ″ will next be positioned on the tilt axis 13 of the elements 14 with each other. When using both the integrator bar and the integrator plates, the number of lens elements located in the integrator plate will be relatively small.

The angle β may be larger or smaller than 45 ° in other spatial light modulators.

Claims (8)

A projection system comprising at least two light sources, a projection lens and at least one spatial light modulator positioned between the light sources and the projection lens, each of which is provided with an element that can be tilted at an angle with respect to the tilt axis. A plurality of light-deflecting devices, wherein the tilt axis extends parallel to each other, the light sources being in operation from the light sources and the centers of the light beams projected on each element being substantially parallel to the tilt axis of the element. And relative to said spatial light modulator in a manner located on said projecting line. A projection system according to claim 1, wherein the optical axes of the light sources cross each other, but the shortest connection line between the optical axes projected on each element of the spatial light modulator coincides with the projection line of the relevant element. The projection system of claim 1 or 2, wherein an integrator system is disposed between the light sources and the spatial light modulator. 4. The projection system of claim 3, wherein the integrator system includes an integrator bar having an inlet side near the light sources and a rectangular outlet side near the spatial light modulator. The projection system according to claim 4, wherein a ratio between the height and the width of the exit side of the rectangle corresponds to the height / width ratio of the spatial light modulator. 6. Projection system according to claim 4 or 5, wherein the height / width ratio is about 7: 4 near the inlet side and about 4: 3 near the outlet side. 7. The integrator system according to any one of claims 3 to 6, wherein the integrator system has at least one integrator plate provided with a plurality of rectangular lens elements, the longitudinal side of which borders the integrator plate is the rectangular lens. An angle with the elements, the angle being substantially equal to the angle between the longitudinal side of the spatial light modulator and the tilt axis. 8. The integrator system of claim 3, wherein the integrator system comprises an integrator bar and at least one integrator plate, the integrator bar being positioned between the light sources and the integrator plate. Characterized in that the projection system.